'use strict'
/**
 * 加解密工具类
 */
const Base64 = {
	_keyStr: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=',
	// 加密
	encode: (data) => {
		let output = ''
		let chr1
		let chr2
		let chr3
		let enc1
		let enc2
		let enc3
		let enc4
		let i = 0
		data = Base64._utf8_encode(data)
		while (i < data.length) {
			chr1 = data.charCodeAt(i++)
			chr2 = data.charCodeAt(i++)
			chr3 = data.charCodeAt(i++)
			enc1 = chr1 >> 2
			enc2 = ((chr1 & 3) << 4) | (chr2 >> 4)
			enc3 = ((chr2 & 15) << 2) | (chr3 >> 6)
			enc4 = chr3 & 63
			if (isNaN(chr2)) {
				enc3 = enc4 = 64
			} else if (isNaN(chr3)) {
				enc4 = 64
			}
			output = output + Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) + Base64._keyStr.charAt(enc3) + Base64
				._keyStr
				.charAt(enc4)
		}
		return output
	},
	// 解密
	decode: (data) => {
		let output = ''
		let chr1
		let chr2
		let chr3
		let enc1
		let enc2
		let enc3
		let enc4
		let i = 0
		data = data.replace(/[^A-Za-z0-9]/g, '')
		while (i < data.length) {
			enc1 = Base64._keyStr.indexOf(data.charAt(i++))
			enc2 = Base64._keyStr.indexOf(data.charAt(i++))
			enc3 = Base64._keyStr.indexOf(data.charAt(i++))
			enc4 = Base64._keyStr.indexOf(data.charAt(i++))
			chr1 = (enc1 << 2) | (enc2 >> 4)
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2)
			chr3 = ((enc3 & 3) << 6) | enc4
			output = output + String.fromCharCode(chr1)
			if (enc3 !== 64) {
				output = output + String.fromCharCode(chr2)
			}
			if (enc4 !== 64) {
				output = output + String.fromCharCode(chr3)
			}
		}
		output = Base64._utf8_decode(output)
		return output
	},
	// utf8加密
	_utf8_encode: (data) => {
		data = data.replace(/\r\n/g, '\n')
		let utftext = ''
		for (let n = 0; n < data.length; n++) {
			let c = data.charCodeAt(n)
			if (c < 128) {
				utftext += String.fromCharCode(c)
			} else if ((c > 127) && (c < 2048)) {
				utftext += String.fromCharCode((c >> 6) | 192)
				utftext += String.fromCharCode((c & 63) | 128)
			} else {
				utftext += String.fromCharCode((c >> 12) | 224)
				utftext += String.fromCharCode(((c >> 6) & 63) | 128)
				utftext += String.fromCharCode((c & 63) | 128)
			}
		}
		return utftext
	},
	// utf8解密
	_utf8_decode: (data) => {
		let string = ''
		let i = 0
		let c = 0
		let c2 = 0
		let c3 = 0
		while (i < data.length) {
			c = data.charCodeAt(i)
			if (c < 128) {
				string += String.fromCharCode(c)
				i++
			} else if ((c > 191) && (c < 224)) {
				c2 = data.charCodeAt(i + 1)
				string += String.fromCharCode(((c & 31) << 6) | (c2 & 63))
				i += 2
			} else {
				c2 = data.charCodeAt(i + 1)
				c3 = data.charCodeAt(i + 2)
				string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63))
				i += 3
			}
		}
		return string
	}
}

export default Base64
